Plural worm drive



p 1953 M. L. VAN OVEREEM 2,651,217

PLURAL WORM DRIVE Filed May 17, 1951 4 Sheets-Sheet 1 Sept. 8, 1953 M. L. VAN OVEREEM 1,2 7

PLURAL WORM DRIVE Filed May 17, 1951 4 Sheets-Sheet 2 Sept. 8, 1953 M. L. VAN OVEREEM 2,651,217

PLURAL WORM DRIVE Filed May 17, 1951 4 Sheets-Sheet 8 a 1 i M j Sept. 8, 1953 M. L. VAN OVEREEM PLURAL WORM DRIVE 4 Sheets-Sheet 4 Filed May 17, 1951 nism can consist of Patented Sept. 8, 1953 OFFICE 2,651,217 PLURAL WORM DRIVE Marius Leonard Hilversum, N

Application May 17, In the Netherl van Overeem, etherlands 1951, Serial No. 226,862 ands May 19, 1950 3 Claims. (Cl. 74724) A device for driving the turntable of a gramophone can be constructed in different ways. The greater the requirements, put at the constancy of the velocity and the value of the mechanical noise level, the more accurate and the more expensive the drive will be.

Physiological experiments have shown, that the variations in the velocity have to be less than 1 pro mille of the average speed. The same requirement is also put to the driving mechanism, which means very accurate manufactures and punctual finish.

In principle an extremely good driving mechaa high running synchro-motor with wormgear. These parts can be made with the required accuracy.

The invention creates the possibility to construct gramophones with one or more different speeds, using original wormgears and keeping the greatest simplicity. Therefore the driving mechanisms are constructed as loose units and consist of a small synchromotor, wormcase with worm and wormwheel gearing, a ballbearing and a freewheel coupling. The only difference among the said units is the proportion of the worm and wormwheel; in other words, the wormzwormwheel proportion stipulates the speed of the turntable.

The said units fit into and upon each other like bricks in a toy box and in this way it is possible to mount up gramophones for 1, 2, 3 and 4 speeds, in accordance with the requirements.

In contra-distinction with known construe tions, the wormwheel has not been borne on an axle, but on a fixed, central and hollow core on the bottom of the wormcase by means of a ballbearing, which bearing affords by its construction a very great stability to the said wormwheel.

The unit ridge, on which the synchromotor has been connected by means of three screw-nuts. The free axle-end of the motor with the worm mounted on it, is directed into the wormcase, by which the worm can be brought into contact with the wormwheel. The three screw-nuts by which the motor has been connected on the ridge of the wormcase, have ample holes at their disposal so that it is possible to remove the motor with the worm in any direction in a vertical field. Herewith a correct mounting between worm and wormwheel can be effected.

As the wormcase is entirely open at the top and perfectly within easy reach, the mounting can be made very simply and easy to control. The intention is that this mounting is performed by the factory. It may be left to the user to mount the units, constructed in this manner, into complete drives with the necessary accessories.

The connection of the wormwheel with a ballcase has been constructed with a l ing accessory will stop.

invention a complete drive consists besides units of a bottomand a topshield and a secondary axle. The said shields over the ballbearing with which the secondary axle is borne.

shaft is substantially supposed with the two ballbearings in the two shields. Although shields and units fit into and on each undesirable effects canbe avoided and any exgame 3 centricity or other deviations can be caught imperceptibly.

The rolls or balls in the freewheel-couplings are locked in a cage, by which they cannot get away. However, they are able to make contact through holes with those parts of the system, which must be coupled, or decoupled. So the freewheel-couplings stay intact during transport or mounting of the units. Although the principle in such a manner of the freewheel-couplings is not quite original, the special construction adapted by the units is of great importance.

It must be known, that the secondary shafts according to the invention have been adapted and manufactured in such a way, that it is possible without any trouble to push them through the units, freewheel-couplings and shields by hand, with which a correct position and collaboration with these freewheel-couplings is reached automatically. That portion of those parts of the shaft operating in and with the freewheelcouplings are therefore manufactured on one diameter, except the lower end, which is conical. In this way it is a very simple manipulation to bring in and to push the shaft through the units and the freewheel-couplings. When the shaft is brought in and pushed through, the rolls of balls of the respective freewheel-couplings are pushed away and are of not any hindrance. As the secondary shaft itself, in contradistinction with known constructions, is coupled with the rolls or balls directly, it is necessary to harden and to grind the shaft in that very place.

The normal process of hardening by heating and cooling has the risk of warping. Moreover the shafts would have to be hardened along nearly their whole length. Therefore a much better and cheaper method is recommended with which the shafts are chromed and polished only in the places, which come into contact with the rolls or balls of the freewheel-couplings. The intermediate parts may remain unpolished.

Now follows an example for a mounting of a drive at three different speeds. First the bottomshield. Upon this a unit, say for 33,33 R. P. M., is mounted; next a unit for 45 B. P. M. and upon this a unit for 78 R. P. Now the respective motors of the three units are fixed under angles of 120 degrees.

A secondary shaft of a fixed length and suitable for a drive at three speeds is now pushed through the units and freewheel-couplings and is pressed with the lower end into the ballbearing of the bottomshield. v

Then the top-shield is pushed over the shaft and is pressed on the highest unit. Three screw bolts are pushed through holes in the wall of each unit case and through the shields and with rings and nuts the units and shields are pressed upon each other just like electro-motors. Herewith a drive at three speeds is ready now.

In this simple way a user can mount according to his wishes and according to what is wanted and he can equip studios and other technical rooms in a most modern way. The drive mounted in such a manner can be coupled with the turntable in a well known way.

The operation is as follows. If for example the lowest unit for 33,33 R. P. M. is switched on, then the freewheel-coupling will be taken up by the wormwheel of that unit; the rolls or balls in the freewheel-coupling and the secondary shaft are going to act like a stiff coupling by which the turntable is driven in a perfectly reliable manner. At the same time the rolls or balls in the freewheel-couplings of the remaining units decouple automatically, because the shaft acts there as the driving part. In this way it is possible to switch over from one unit, or speed to the other at once. Even mistakes in switching, by which two or three units would be set into action at the same time, can have no disadvantageous results. The unit having the highest speed will have the leading part in the action. It drives the secondary shaft and also the turntable, while the shaft remains uncoupled automatically in respect of the other units.

A more detailed description of the invention will follow hereunder in connection with the pictures.

Fig. 1 is a top-view of a complete driving-unit constructed in this invention. v

Fig. 2 is a cross-section via line 11-11 of Fig. '1;

Fig. 3 is a cross section of a complete driving system for two speeds. The part freely project ing of the secondary shaft has been represented in this picture as broken off; the shaft can be made as long as necessary for a coupling with the turntable.

Fig. 4 represents the construction and action of a freewheel-coupling according to the invention on a larger scale.

A driving-unit according to Figs. 1, 2 and 3 consists of a synchromotor i of the one-phasetype with condenser-starting. Said motor I has been connected on the ridge of the unitcase 3 by means of three screw-bolts 2. A worm 4, mounted on the free shaft-end of the said motor, directing into the wormcase is in collaboration with a wormwheel 5, which has been supported on a ballbearing 6, which bearing affords by its construction a very great stability to the said wormwheel 5.

Said screw-bolts 2 have ample holes at their disposal, so that it is possible to remove the motor I with worm 4 over the ridge of the unitcase 3 in any direction ina vertical field and to reach a correct mounting and collaboration between worm t and wormwheel 5.

The connection of the wormwheel 5 with the ball bearing '5 on a fixed, central and hollow core on the bottom of the unit case 3, acts as a complete mounted gearing, which can simply be set turning and can be controlled, whereto the unit case 3 is entirely open at the top and perfectly within easy reach.

Said central core on the bottom of the unit case 3 rises above the oil level and excludes the leaking or flowing away of oil. The worm 4, however, can yet take oil enough in order to lubricate the wormwheel 5 and itself sufficiently.

As for a drive at different speeds more driv ing-units are required, in which action always only one unit must be working, every unit is equipped with a freewheel-coupling. The construction and the operation of a freewheel coupling can be explained most clearly with Fig-'- ure 4.

The coupling consists of a segment-disc 9 of hardened steel, said disc being, if desired, locally ground. The three segments and the disc form one unit obtained by fraising and grinding the disc. The disc 9 lies with suflicient play around the secondary shaft 20. Between said shaft and each segment of the disc 9 hardened steel rolls in are provided. Said rolls III are under light pressure by means of the sleeves II and the springs. H. The rolls l0, sleeves H and springs l2 are arranged in a cage l3, enclosed between the three segments of the disc 9 thereto by means of three screws I 4.

The sleeves I I and the springs I2 can be introduced from the outside into the cage I3 and can be secured by means of the screws I5.

and fastened too small to allow so that they cannot during assemblage wheel 5, the rollers I0 close up between the shaft 20 and the segments of the disc 9 and act as a rigid coupling so that the shaft 20 is rotated in an entire reliable manner.

If on the other driven clockwise,

a lower shield 16, and by an upper shield I8 provided with a ball-bearing I9 and further with the secondary shaft 20 and tensioning bolts 2| with rings 22 and nuts 23.

The shields I6 and I8 form a perfect closure for the driving units. The ball-bearings I7 and I 9 serve as a centric support for the secondary shaft 20. passes through the hollow core of the unit cases 3, the cage I3 and the disc 9 without contact and the only contact with a driving unit is obtained by the rollers I0 of each freewheel-coupling.

A condition for the correct operation of the system is that the freewheel-coupling, i. e. the segment independently tral core of the unit-case 3.

The secondary shaft 20 is supported independently by means of the ball-bearings I1 and I9 in the shields I6, I 8.

20 and wear in the freewheel-couplings.

An important characteristic feature of the freewheel-coupling according to the invention is that may consist of rubber pats or steel springs. A fiat ring is very simple and can take up important deviations.

The special construction of the disc 9 enables to introduce the secondary shaft without more by hand through the mounted units in which case automatically contact and the correct cooperation with the freewheel couplings is obtained.

The part of the shaft 20 within the units is finished on one single diameter with the exception of the lower end, which is conical so that it is very simple to pass said shaft through the units and the couplings. In introducing the shaft 20 the rolls ID are pushed laterally and do not form any obstruction.

The shaft 20 itself being coupled with the rolls I0 without the aid of other components it is necessary to harden and to grind the shaft locally.

The normal hardening process by means of heating and cooling shows the risk of warp, which cannot always be corrected by grinding. In that case it would be necessary to harden the shafts over the whole length.

A characteristic feature of the shafts according to the invention is that only at the place of contact with the rolls ID the shafts are hardchromised and ground. The further parts need are pulled together by means of a number of draw-bolts 2 I, washers 22, and nuts 23.

For that purpose the walls of the unit cases 3 are provided with a number of e. g. six continuous channels in such a Way, that for a driving mechanism with one single number of revolution two draw-bolts, for a mechanism with two diiferent numbers of revolution three bolts and for a mechanism with four numbers of revolution four draw-bolts can be used.

I claim:

1. A synchro-motor and worm-transmission driving mechanism for the turntable of a phonograph comprising a plurality of separate driving units each corresponding to a different driving speed, and a driving shaft provided with a ballbearing therefor, each driving un1t consisting of a synchro-motor, a worm-transmission, a freewheel coupling and an elastic coupling between said worm-transmission and said free-wheel coupling, said worm-transmission comprising a worm-wheel, a cylindrical housing about the driving unit provided with a bottom plate, said housing forming a flat unit in which the freewheel coupling is arranged, said worm-wheel being supported on a ballbearing and centrally mounted on said cylindrical housing, each of said driving units together with their respective couplings being rotatably engaged against the driving shaft to fit against each other, and a closing shield encasing the ends of the plurality of driving units.

2. A driving mechanism as in claim 1 wherein said driving shaft is vertically disposed in said housing and wherein said housing is provided with a concentric inner wall surrounding said shaft, the upper ridge of said wall projecting beyond said transmission and said ballbearing to provide an annular oil container for the moving elements of the driving mechanism.

3. A driving mechanism as in claim 1 wherein each freewheel coupling consists of a metal ring coupled to the corresponding wormwheel With a rubber ring, said freewheel coupling being provided with segmented members and springs pressing said segmented members against an annular portion of the surface of said shaft, and wherein said shaft is hardened by chromizing.

MARIUS LEONARD VAN OVEREEM.

References Cited in the file of this patent UNITED STATES PATENTS 

